The subject of this invention is a method and composition for the oxidative coloration (dyeing) of hair, based upon developer substances and coupler substances, in which certain derivatives of 2,6-diamino-pyridine is employed as coupler substance.
Oxidation dyes have acquired a substantial importance for hair coloration. The coloration is produced herewith by means of the reaction of certain developer substances with certain coupler substances in the presence of a suitable oxidation agent.
As developer substances, preferably 2,5-diamino-toluene, 4-amino-phenol and 1,4-diamino-benzene are employed. However, also 2,5-diamino-anisol, 2,5-diamino-benzyl alcohol, 2-(2'-hydroxyethyl)-1,4-diamino-benzene and 4-amino-N-(2'-mesylaminoethyl)-aniline have acquired a certain importance. In determined cases, also tetraamino-pyrimidine can be employed as developer substance.
The preferably employed coupler substances are 1-naphthene, resorcin, 4-chloro-resorcin, m-aminophenol, 5-amino-ocresol and derivatives of m-phenylenediamine, such as e.g. 2,4-diamino-phenetol and 2,4-diamino-anisol. These derivatives, as well as the m-phenylenediamine itself, have acquired herewith a significance as so-called "blue couplers" on account of their capacity to produce blue tones upon the oxidative coupling with 1,4-diamino benzene or 1,4-diamino benzene derivatives.
Numerous particular requirements are placed upon oxidation dyes that are employed for the coloration of human hair. Thus, they must be harmless from both a toxicological and dermatological viewpoint, and make possible the provision of colorations of the desired intensity. It is necessary, moreover, that a broad palette of the most different color nuances can be produced by means of combination of suitable developer and coupler components. In addition, a good fastness to light, permanent waving, acid and rubbing, are required of the obtainable hair colorations. At the very least, such hair colorations must remain stable over a time period of 4 to 6 weeks without being affected by light, chemical agents and rubbing.
The m-phenylenediamine employed for some time as blue coupler in hair coloring compositions, its derivatives 2,4-diamino-toluene and 2,4-diamino-anisol, as well as blue couplers recommended more recently, such as for example 1-hydroxy-3-amino6-chloro-benzene and 2,4-diamino-phenoxyethanol, can not, however, completely satisfactorily fulfill these above mentioned requirements.